The present invention relates to a solenoid valve device.
A conventional solenoid valve device of this type includes a sleeve, a spool, and a solenoid that moves the spool in the axial direction. The sleeve has a cylindrical valve chamber that is formed with an input port, an output port, a drain port, and a feedback port as various ports through which operation oil flows in and out. The spool is a shaft-like member accommodated in the valve chamber, and has a plurality of lands with a cylindrical shape whose outer diameter is generally equal to the inner diameter of the valve chamber, as well as a communication portion that has a cylindrical shape whose outer diameter is smaller than the outer diameter of the lands and communicates between the ports. (See Japanese Patent Application Publication No. JP-A-2004-176895, for example.)
An electromagnetic pump has also been proposed that pressure feeds fluid by repeated excitation and non-excitation of an electromagnetic coil. (See Japanese Patent Application Publication No. JP-A-2007-126974, for example.) This electromagnetic pump has a spring member that uses elastic force to press a piston that forms a pump chamber, and is also provided with an electromagnetic coil that generates a suction force in a direction opposite the elastic force of the spring member. Non-excitation (an off state) of the electromagnetic coil causes the elastic force of the spring member to move the piston, whereby fluid is intaken. Excitation (an on state) of the electromagnetic coil causes the suction force of the electromagnetic coil to move the piston, whereby the intaken fluid is discharged.